Labour leader Jeremy Corbyn has again apologised for hurt caused to Jewish people by anti-Semitism in his party.
In a video message, he also admitted Labour had been too slow in dealing with disciplinary cases.
It comes as his deputy Tom Watson warned the party could “disappear into a vortex of eternal shame” and be unfit to lead if it did not tackle the issue.
He gave a stark warning in The Observer, saying Labour had to take a “long, hard look at ourselves”.
Mr Watson also said the party leader should fully adopt an international definition of anti-Semitism, which Labour’s ruling body has so far resisted, and called for internal inquiries into Jewish Labour MPs Margaret Hodge and Ian Austin to be dropped.
His calls were not addressed in Mr Corbyn’s message, which was posted on Twitter.
In it, the party leader said anyone who denies that anti-Semitism is “surfacing” in the party is “clearly actually wrong and contributing to the problem”.
“I’m sorry for the hurt that’s been caused to many Jewish people,” he said. “We have been too slow in processing disciplinary cases of, mostly online, anti-Semitic abuse by party members. We’re acting to speed this process up.”
Mr Corbyn also stressed that people who hold anti-Semitic views “have no place in the Labour party” and said people who use “anti-Semitic poison” are not his supporters, nor do they speak for him or the party.
He has repeatedly condemned anti-Semitism and has previously said he is “sincerely sorry”.
But The Campaign Against Antisemitism criticised the video for being “insincere” and said Mr Corbyn had failed to address his own issues with anti-Semitism.
Gideon Falter, chairman of the group, said: “Jeremy Corbyn has released yet another bland statement devoid of any apology for his own anti-Semitism or promises of specific actions.
“In his Guardian article on Friday he called our concerns ‘overheated rhetoric’ and in this video he says that our concerns must not be dismissed.
“It is just another contradictory, hypocritical, insincere attempt to whitewash his own role as the author of this nightmare.”
The Jewish Leadership Council and Board of Deputies have accused the Labour leader of “ideological hostility” to the International Holocaust Remembrance Alliance (IHRA) definition of anti-Semitism and its 11 examples.
While Labour’s code has adopted the definition, it misses out four of the examples.
Sunday’s video comes after Mr Corbyn wrote a piece in the Guardian on Saturday, in which he resisted the same demand over the IHRA definition from others.
In his article, he said he recognised the “strong concerns” about Labour’s code of conduct and that many Jewish organisations believed it should include all examples.
But Mr Corbyn, a long-standing supporter of the rights of Palestinians, defended Labour’s decision not to include one of the examples – which warns against “claiming that the existence of a State of Israel is a racist endeavour”.
He said this had “sometimes been used by those wanting to restrict criticism of Israel that is not anti-Semitic”.
The article was criticised by members of the Jewish community, including the Jewish Labour Movement, who said: “There is no trust left. We find ourselves asking once again for action, not words.”
Mr Watson said Labour needs to “stand up for what is right and present the party as fit to lead the nation”.
He said it was important to “de-escalate this disagreement”, and believed that it should start with dropping cases against MPs Mrs Hodge and Mr Austin.
The Labour MPs, who both lost family members in the Holocaust, are facing disciplinary proceedings for confrontations over the party’s response to anti-Semitism claims.
Mr Watson said: “I have frequently had very difficult conversations with both Margaret and Ian, but what I understand is that your critics are not your enemies.
“On an issue that is so dear to them, I think people are very, very concerned that these investigations should be dropped quickly.”